Orchiectomy will remove the testosterone stimulus prostatic cancer cells are dependent upon for growth and division. With removal of this stimulus, the cells will undergo apoptosis (scattered shrunken cells are apoptotic bodies).

The other answers are unlikely:

• Corpora amylacea are small hyaline masses in the prostate gland of unknown significance. It would not be a change from normal to find these.
• Edema is unlikely as this is more characteristic of diseases like prostatitis where inflammatory cytokines cause leaky blood vessels. Orchiectomy would not cause prostatic inflammation.
• There is no stimulus for hypertrophy and rather with orchiectomy you are removing a growth stimulus.
• Necrosis of the blood vessel walls is not likely because the blood vessels are not affected by the loss of the androgens, rather the actual prostatic cells are.
• Widespread necrosis is also not likely as this is not the mechanism of death after testosterone removal (death will occur by apoptosis rather than necrosis) and widespread necrosis is more characteristic of infarct or something that causes massive sudden tissue death.